1. Technical Field
The present invention is directed to a rebound cushion for an automotive vehicle or truck. More particularly, the present invention is directed to a rebound cushion assembly used in conjunction with a vehicular body mount in which the vertical cushioning rate and the lateral cushioning rate may be tuned independently from each other.
2. Discussion
Automotive vehicles, and especially trucks are typically equipped with a body mount disposed between the vehicle body and the vehicle frame. The body mount provides additional cushioning between the vehicle body and frame. The body mount also serves to isolate the transmission of vibration energy and impact energy from the vehicle suspension and frame up through the vehicle body.
A rebound cushion is typically used in conjunction with the body mount for providing additional cushioning and vibration damping characteristics. A variety of rebound cushions have been developed for different types of vehicle applications. Most of these rebound cushion designs include an elastomeric member which is captured by a support structure for securing the rebound cushion in relation to the body mount. The elastomeric member may be formed from a variety of plastic or rubber materials.
One example of a simple compression style rebound cushion is a circular or annular elastomeric member which is retained in place by a metal plate and suitable fastener. The durometer of the elastomeric member can be chosen for tailoring the characteristics of the rebound cushion. However, this compression style rebound cushion is stiff vertically and soft laterally; including both side to side and fore/aft lateral directions. A particular disadvantage of this simple rebound cushion design is that it does not provide firm lateral support for the vehicle body with respect to the frame. Thus, the vehicle body is able to move in the side to side and fore/aft directions with respect to the frame. This soft lateral support can allow excessive motion laterally with respect to the vehicle frame which results in poor shake control of the vehicle.
An additional disadvantage of this compression style rebound cushion design is that stiffening the lateral cushioning rate produces a firm vertical cushioning rate which absorbs less energy and provides a harsher ride. Moreover, this rebound cushion design typically has a vertical to lateral cushioning rate ratio of approximately 3:1 (vertical:lateral), allows only minimal tuning of the vertical rate with respect to the lateral rate, and limited options for designing the vertical rate independently from the lateral rate. Accordingly, this type of rebound cushion provides limited design flexibility to a vehicle ride control engineer in designing the rebound cushion for use on a variety of vehicles.
In the design of vehicle suspension systems, it is becoming more common to require the rebound cushion and body mount to have a soft vertical cushioning rate for enhancing ride comfort, and a firm lateral (meaning both side to side and fore/aft) cushioning rate for providing increased vehicle stability and control. However, this desired feature typically requires a rebound cushion and sometimes a body mount in which the vertical cushioning rate and the lateral cushioning rate can be tuned or designed independently from each other.
In view of the disadvantages associated with the prior art rebound cushion and body mount designs, it is desirable to provide a rebound cushion which has a soft vertical cushioning rate and a firm lateral cushioning rate. It is further desirable to provide a rebound cushion which has a vertical to lateral cushioning rate of 1:2, 1:3 or greater, while still maintaining a soft vertical rate. Finally, it is desirable to provide a rebound cushion having a low cost retaining feature so that all of the components forming the rebound cushion assembly can be retained in a preassembled state without the use of a fastener or adhesive.